JPS63295652A - Hydrophilic porous material - Google Patents

Abstract

PURPOSE:To obtain a hydrophilic porous material which is inexpensive, excellent in strength, rigidity, dimensional stability, etc., and suitable for an element of a humidifier or the like, by mixing a polyethylene powder of specified properties with an inorganic filler and two specified surfactants and sintering the mixture. CONSTITUTION:100pts.wt. polyethylene powder (A) of a melt index <=0.3g/10min, an angle of repose of 27-40deg., an average particle diameter of 20-150mu, a content of particles of a particle diameter <=200mu >=90wt.%, and a bulk density of 0.3-0.55g/cc is mixed with 0.05-2pts.wt. inorganic filler (B), 0-3pts.wt. sulfonate anionic surfactant (C), and 0-3pts.wt. nonionic surfactant (D) selected from among a polyoxyethylene (sorbitan) fatty acid ester, (poly)glycerol fatty acid esters, etc. such that 3pts.wt. >=C+D>=0.05. This mixture is sintered to obtain a hydrophilic porous material of an average porosity of 30-55vol.%.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hydrophilic porous body of polyethylene resin powder. For more information, please refer to humidifiers, moisturizers, anti-condensation devices,
Humidity controllers, etc. can absorb, emit, permeate, and absorb water (in the present invention, the word water includes water vapor, moisture, etc.).
The present invention relates to a hydrophilic porous material that effectively acts as an element that can be induced.

(Prior art and its problems) In recent years, with the development of air conditioning equipment such as air conditioning and heating equipment, the number of living spaces that use it is also expanding.

On the other hand, such living spaces have become highly airtight in recent high-rise housing and urban housing, and humidification or humidity control has become increasingly important as well as air conditioning.

Furthermore, by keeping the inside of electronic and electrical equipment under a certain level of humidity, it is possible to extend the life of the equipment and prevent the generation of static electricity. Low-temperature preservation of fresh foods is becoming more and more popular, and humidity control is becoming an important factor in this as well. In recent years, there has been an active movement to actively control not only temperature (but also humidity) as a way to control the environment, and a representative method is hydrophilic technology that can easily absorb, diffuse, diffuse, permeate, and guide water. The use of a porous material as the element is disclosed in, for example, Japanese Patent Application No. 255032/1982 and Japanese Patent Application No. 12170/1982.

The hydrophilic porous body referred to in the present invention is used for humidifiers, moisturizers, dew condensation preventers, humidity controllers, heat exchangers, and the like. It must have sufficient functionality to absorb, diffuse, diffuse, permeate, and guide water. For example, when used in a humidifier element, when the lower part of a hydrophilic porous body (rectangular plate) is immersed in water, water rises through the porous body due to capillary action, but the rate of rise is as fast as possible, and the is desired to easily diffuse into the porous material. Also, the use of this porous material in the openings of cold storage containers as a dew condensation preventer is being considered, but even in such cases, water droplets may adhere to the surface of the porous material. The water droplets must be absorbed into the pores of the porous body as quickly as possible. That is, the hydrophilic porous body that is the object of the present invention must be able to absorb water quickly in its pores and easily diffuse into each part of the porous body, and the porous body must be able to absorb water easily. It is essential that the material be a porous material having pores. Furthermore, it is desirable that such a decrease in hydrophilicity due to repeated entry and exit of water be as small as possible. or,
It is required that there is no dimensional change or strength change due to water absorption.

Hydrophilic polymers are often used as such hydrophilic open porous materials because they can easily absorb, emit, permeate, and guide water, such as polyvinyl alcohol. Examples include water-absorbing polymer materials such as MMA resin, polyacrylic acid salt system, isobutylene-maleic acid copolymer system, starch-acrylic acid graft copolymer, and saponified vinyl acetate-acrylic acid ester copolymer. However, these materials not only cause a decrease in strength due to water absorption, but also undergo large dimensional changes when water is absorbed because the polymer itself absorbs water. Materials made of natural fibers such as cloth or paper are inherently inferior in strength and rigidity, and making them as strong as a molded product would be costly and impractical. That is, until now, there has been no hydrophilic porous material that can be produced industrially and has excellent strength, rigidity, and dimensional stability.

As a result of intensive studies to solve such problems, the present invention has been completed.

(Means for Solving Problems and Effects) The present invention consists of: 1) (a) A polyethylene powder having a melt index of 0.3 g/10 minutes or less, an angle of repose of the powder of 27° to 40″, and a particle size distribution of The average particle size (50% particle size) is 20 to 150μ, and 901i amount% or more of the total particle size is 200μ.
μ or less and a bulk density of 0.30 to 0.55 g/cc polyethylene powder (A) 100 parts by weight, (b) inorganic filler (B) 0.05 to 2.0 parts by weight, and (e) sulfone. Acid type anionic surfactant (C)
0-3. Offi amount and (d) polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester,
One or more nonionic surfactants selected from polyoxyethylene fatty acid ester, polyglycerin fatty acid ester, glycerin fatty acid ester, and sorbitan fatty acid ester (D) O~3.0 parts by weight and 3 (A), (13), (C) and (b) where .0 part by weight ≧ (C) + (D) ≧ 0.05 part by weight.
It is formed by sintering after mixing the ingredients, and has an average porosity of 30 to 55.
Hydrophilic porous material that is % by volume.

2) A hydrophilic porous material in which the polyethylene powder according to item 1 above is a polymerized powder of ethylene and is produced by suspension polymerization of ethylene.

3) A hydrophilic porous material in which the inorganic filler (B) in item 1 or 2 is silica, calcium carbonate, or a mixture thereof.

4) A method for producing a hydrophilic porous material, in which the temperature of the materials to be mixed is 50 to 125°C during the mixing in Items 1 to 3 above.

5) During the mixing in Items 1 to 3 above, 0.05 to 1.0 parts by weight of water is allowed to coexist with 100 parts by weight of polyethylene powder, and the temperature of the mixture is kept at 60°C to 125°C. A method for producing a hydrophilic porous material to be mixed.

I will provide a.

In the present invention, raw materials for the hydrophilic porous material having the functions of absorbing, dissipating, permeating, and guiding water include those that have excellent chemical resistance and exhibit no dimensional change due to absorption, and those that exhibit no decrease in strength due to water absorption. Polyolefin resins are preferable because they are free, low in cost, can be produced by hand in large quantities at low cost and stably, and have sufficient strength as a sintered body. Among polyolefin resins, particularly preferred is ethylene polymer powder, which is easily available as a powder, allows control of particle size and particle size distribution, and has good sintering formability. Such ethylene polymer powders are obtained by ethylene suspension polymerization, and the powder shape is spherical, elliptical, or similar, with clear edges, ridges, and thread-like or whisker-like shapes. It is essentially free of substances, has extremely good fluidity as a powder, and has excellent sintering formability.

Polyethylene resin powder can also be obtained by mechanically or chemically pulverizing polyethylene pellets; % particle size) is 20 to 150 μ and 9 of the total
0% by weight or more is 200μ or less, bulk density of powder is 0.30
Such powders, which should be ~0.55 g/cc, can be obtained by cold mechanical grinding, cryogenic grinding, chemical grinding, etc.

ASTM D 1238 (
In the present invention, it is necessary that the melt index at a load of 2.16 kg and a temperature of 190° C. be 0.3 g/l 0 min or less. If the melt index exceeds 0.3, the powders tend to fuse together during sintering, causing clogging of necessary pores, lowering the porosity, and making the material unsatisfactory as a continuous porous material. A more preferable range for the melt index is 0.2 g/10 minutes or less.

In the present invention, the particle size distribution of the powder conforms to JIS Z-8801.
Sieve residue test method using a sieve (JIS K6
069). The test method yields a cumulative distribution curve. The 50% particle size of this cumulative distribution is determined as the average particle size. In the present invention, the particle size distribution of the powder has an average particle size (50% particle size) in the range of 20 to 150μ,
It is necessary that at least 90% by weight of the whole particle size is 200μ or less, and more preferably 50% particle size is 30 to 120μ.
More than 90% of the total particles have a particle size of 200μ or less. If the average particle size (50% particle size) is less than 20 μm, the powder is too fine and the sintered porous body is severely clogged and does not have the characteristics of a continuous porous body. Moreover, the porosity also decreases.

In the present invention, the angle of repose is preferably in the range of 27'' to 40''. When the angle of repose is less than 27°, the fluidity of the powder becomes excessively good, resulting in a decrease in the porosity of the porous body after sintering. On the other hand, if the angle exceeds 40°, the fluidity of the powder will be extremely deteriorated, and the porosity will become too large or the porosity will become uneven in various parts of the porous body.

Powder bulk density is defined by ASTM D 1895. In the present invention, the bulk density is 0.33 to 0.55 g
/cc is preferably used. Bulk density is 0.33
If it is less than this, the fluidity of the powder will be poor and even if it is sintered, the porosity will be too large or the porosity will be uneven locally. As a result, water is insufficiently guided. On the other hand, if the bulk density exceeds 0.55, the sintered porous body will easily become clogged, and water absorption and induction will become insufficient without losing the characteristics of a continuous porous body.

It is preferable that the polyethylene powder in the present invention be produced by suspension polymerization, since it can simultaneously satisfy the powder characteristics specified in the present invention, and also from the economic point of view.

The polyethylene polymer of the present invention may be copolymerized with other monomers as long as it has the above-mentioned properties. Polyethylene powder having such properties can be produced, for example, by the method described below.

Ethylene polymerization can be carried out by an olefin polymerization reaction using a Ziegler type catalyst. For example, a catalyst using an organomagnesium component and a transition metal compound that is soluble in a hydrocarbon solvent, or a catalyst based on an alumosiloxane and a transition metal compound, etc., can be used at the polymerization temperature in the presence of an α-olefin if necessary in the polymerization solvent. is room temperature to 10
It can be produced by a method in which ethylene is polymerized at 0° C. and a pressure that maintains the polymerization system in a suspended state. The ethylene polymer powder obtained by the method described above can be further subjected to mechanical grinding using a high-speed mixer such as a Henschel mixer or various types of grinders as a post-processing step. . It is also possible to change the particle size distribution etc. by performing arbitrary sieving operations.

The most important point in the present invention is that the sintered compact has hydrophilic properties. Even if the polyethylene powder is simply sintered and molded, since polyethylene is originally hydrophobic, it does not show any wood-philicity.

In order to obtain a sintered body having hydrophilic properties, an inorganic filler (
B) and sulfonic acid type anionic surfactant (C) and polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, polyoxyethylene fatty acid ester, polyglycerin fatty acid ester, glycerin fatty acid ester, and sorbitan fatty acid ester Only a porous body obtained by adding a certain amount of one selected nonionic surfactant or a mixture (D) of two or more types, (dry) mixing, and then sintering,
Water can be easily absorbed into the pores of the sintered body, the water can easily diffuse throughout the porous molded body by capillary action, and the porous body does not show any dimensional or strength changes due to water absorption. This discovery led to the present invention.

In the present invention, inorganic filler (B) includes silica, calcium carbonate, magnesium carbonate, clay (kaolin clay, waxite clay, talc, sericite, calcined clay), silicate mineral, mica, bentonite (calcium silicate, Zeolite) Refers to natural silicic acid, alumina hydrate, barium sulfate, calcium sulfate, etc., and one of them may be used alone or a mixture of two or more thereof may be used. In particular, silica or calcium carbonate is preferably used in the present invention.

Silica is divided into wet process silica and dry process silica depending on the manufacturing method, but the former includes Hisil, for example.
, Nip Seal, Jilton or the latter Aero
It is commercially available under the trade name sil, etc., and any of them can work well. Polyethylene powder 10 as inorganic filler
It is added in an amount of 0.05 to 2.0 parts per 0 parts by weight. Although the effect of the inorganic filler on the sintered body of the present invention has not been completely clarified, it is thought to have the following meaning. That is, by adding an inorganic filler, the powder fluidity of the powder composition of the present invention is improved, so that the size and distribution of pores as a sintered porous body after sintering becomes uniform, or Sintering has the advantage of making it possible to sinter mold objects with somewhat complex shapes, but an even more important function of the present invention is that the inorganic filler adheres to the surface of the polyethylene powder and is sintered. It is thought that this sometimes limits the fusion of polyethylene powders to each other to some extent. In other words, during sintering, the polyethylene powder melts and fuses together to form a continuous porous body, but the fusion becomes excessive (hereinafter referred to as an oversintered state), and as a result, the pores become clogged. However, it is thought that the filler can prevent this from happening. As the inorganic filler (Is), calcium carbonate and silica are particularly effective for these effects.

The amount of inorganic filler added is preferably 0.05 to 2.00 parts by weight. If it is less than 0.05 part by weight, the powder will not have good fluidity and the effect of preventing oversintering will be insufficient, the size of the pores in the sintered compact will be non-uniform, and the porosity in many parts of the sintered compact will be low. If the amount of inorganic filler exceeds 2.0 parts by weight, sintering will be insufficient, i.e., the fusion of polyethylene powders will increase. It is easy to cause poor adhesion, and the strength as a molded product is insufficient, causing problems such as cracking and chipping.

In the present invention, it is important to add a specific surfactant to impart hydrophilicity to the sintered porous body. It has been found that good hydrophilicity as referred to in the present invention can be obtained only by combining the specific polyethylene polymer powder, a specific inorganic filler, and a specific surfactant. The surfactants used in the present invention include sulfonic acid type anionic surfactants (C), polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, polyoxyethylene fatty acid esters, polyglycerin fatty acid esters, and glycerin fatty acid esters. (D) is a mixture of one or more nonionic surfactants selected from esters and sorbitan fatty acid esters, and (C)
, (D) are added and mixed in a range of O to 3.0 parts by weight, and in a range of 0.05≦(C) + (D)≦3.0 (parts by weight). The sulfonic acid type anionic surfactant (C) is added in an amount of 0 to 3.0 parts by weight, but if it is added in excess of 3.0 parts by weight, the fluidity of the powder deteriorates and sintering becomes difficult. Otherwise, the strength of the sintered porous body decreases. Examples of the sulfonic acid type anionic surfactants include alkyl sulfonates, alkylnaphthalene sulfonates, alkylbenzene sulfonates, succinic ester sulfonic acids, and alkyldiphenyl ether ditolphonates. In the present invention, alkyl sulfonates of 01□ to CRt are more preferably used.

The nonionic surfactant (D) is added in an amount of 0 to 3.0 parts by weight, but if it exceeds 3.0 parts by weight, the fluidity of the powder deteriorates and sintering becomes difficult. The strength of the product will decrease.

Examples of the nonionic surfactants according to the present invention include the following.

Examples of polyoxyethylene sorbitan fatty acid esters include polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monoisostearate, polyoxyethylene sorbitan tristearate, Examples include polyoxyethylene sorbitan monooleate and polyoxyethylene sorbitan triolate. Examples of the polyoxyethylene sorbitol fatty acid ester include polyoxyethylene sorbitol tetraoleate and the like. Examples of polyoxyethylene fatty acid esters include polyethylene glycol monolaurate, polyethylene glycol monostearate, polyethylene glycol distearate, and polyethylene glycol monooleate.

Examples of the polyglycerin fatty acid ester include polyglycerin monoisostearate, polyglycerin monolaurate, polyglycerin monostearate, polyglycerin monooleate, diglycerin monolaurate, and the like. Furthermore, examples of glycerin fatty acid esters include glycerin monocaprylate, glycerin monolaurate, glycerin monostearate, and glycerin monooleate, including those purified by molecular distillation.

Sorbitan fatty acid ester nonionic surfactants include sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan tristearate, sorbitan monooleate, sorbitan triolate, sorbitan sesquioleate, sorbitan distearate, Examples include sorbitan monobehenate.

As the sorbitan fatty acid ester nonionic surfactant, one having 2 or more of L and B is more preferable and is applicable to the present invention. These nonionic surfactants may be used alone or in combination of two or more.

In the present invention, the above two types of surfactants (C) are used.

(D) is preferably used in combination. In the present invention, the surfactants (C) and (D) of 2!1i are 0.0
It is added in a range of 5 parts by weight ≦ (C) + 53.0 parts by weight (D).

If (C) + (D) is less than 0.05, the hydrophilicity as defined in the present invention will be insufficient, and if (C) + (D) exceeds 3.0 parts by weight, the fluidity of the powder will deteriorate and sintering will occur. It becomes difficult to form the sintered porous body, and the strength of the sintered porous body is extremely reduced.

A more preferable range is 0.1≦(C)+(D)
The range is ≦1.0.

Wood-philicity in the present invention is achieved only by the combination of the specific polyethylene polymer powder (A), inorganic filler (B), surfactants (C), and (B). The agent (C) is effective in imparting initial hydrophilicity to allow water to be easily absorbed and diffused into the hydrophilic porous material, and the surfactant (D) is effective in providing the hydrophilicity for a long period of time. In other words, it is mainly effective in maintaining its hydrophilicity even if a hydrophilic porous material repeatedly absorbs water, evaporates as diffusion, evaporates, or permeates water.
It has been discovered that by combining (C) and (D), it is possible to obtain a hydrophilic continuous porous material that has excellent initial hydrophilicity and excellent sustainability of its hydrophilicity.

It is important that the above composition of the present invention is mixed uniformly by dry mixing. In particular, inorganic filler (B), surfactant (C), (
It is important to uniformly disperse and adhere D). As the (dry type) mixer, various blenders such as a high-speed mixer (for example, Henschel mixer), a ribbon blender, and a drum blender having a high-speed stirring blade can be used, but a high-speed mixer having a high-speed stirring blade is preferable. (Dry method) When mixing, keep the temperature of the powder at 50°C or higher and 125°C.
The following procedure is a preferred method for uniform dispersion. More preferably, the temperature is 70°C or higher and 120°C or lower.

Also, during (dry) mixing, 0.05 parts by weight to 1 part by weight, preferably 0.05 parts to 0.5 parts of water, per 100 parts by weight of polyethylene powder may be present in the coexistence of (dry) mixing. This is a more desirable attitude. The temperature during mixing in the presence of water should be 70°C or higher and 125°C or lower, more preferably 80°C or higher and 125°C or lower. Note that if the mixture is normally mixed under the above conditions, there will be almost no remaining water at the end of the mixing, but if any water remains, it is preferable to remove the water by an appropriate method (for example, hot air drying). In this way, water coexists (
When mixed (dry), the hydrophilic porous material finally obtained has excellent wood-philicity.

Water may be allowed to coexist with the mixture by adding water at the time of mixing, or by adding it to the polyethylene polymer powder, inorganic filler, or surfactant in advance. The mixture further includes a coloring agent which is usually added to the polymeric material for molding;
It is also possible to add heat stabilizers, mold release agents, etc.

The thus obtained mixture containing polyethylene powder as the main raw material is a powder mixture in which the inorganic filler and surfactant are uniformly adhered to the surface of the polyethylene powder. The powder mixture then enters a sintering process. As the sintering and shaping method, a method normally applied to thermoplastic resin powder is used.

For example, it can be easily carried out industrially by filling a mold with the powder mixture, then introducing the mold into a heating furnace, taking out the mold, cooling it, and taking out the sintered compact from the mold. When filling a powder mixture into a mold, it is preferable to apply vibration to the mold by an appropriate method in order to uniformly fill every corner of the space in the mold with the powder. However, if too strong vibration or long-term vibration is applied, the porosity of the porous body after sintering will be less than 30% by volume, and the hydrophilic porous body will easily become clogged. Performance such as absorption, diffusion, and transmission may be inferior. In addition, if no vibration is applied at all and the shape of the sintered molded product is complex, the porosity will exceed 55% by volume, and in this case too, the pores will become too large and the diffusion of water due to capillary action will only decrease. However, the porous body obtained by sintering has a porosity of 30 to 55 volume even if vibration is applied during filling, which is not preferable for the porous body of the present invention because it is brittle and has low strength. It must be controlled in the present invention so that it falls within %.

Appropriate heating means can be used to heat the mold, such as introducing the mold into a heating furnace, heating using a high-frequency heating method, and immersing the mold in a high-temperature salt bath. The heating conditions are mainly temperature and time, and these must be changed greatly depending on the size and thickness of the molded product, but the surface temperature of the mold after heating and immediately before cooling should be between 130°C and 200°C.
The value is 100 yen. If the heating is excessive, the porous material obtained will become clogged, and in some cases, the porosity will be less than 30%, and the material will no longer be able to function as a hydrophilic porous material according to the present invention. In addition, if the heating is insufficient, the porous material becomes brittle and cannot perform its function as a hydrophilic porous material.The heating conditions are also similar to the filling conditions. Porosity is 30-55% by volume
It must be controlled so that it can come in between.

Note that the porosity (%) referred to in the present invention is determined by the following formula.

Apparent specific gravity (ρt) = W (g) / V (am') Porosity (%) = [true specific gravity (ρ.) - apparent specific gravity (ρI)] xl
Q" A porous material easily absorbs, diffuses, and permeates water, and maintains sufficient strength and rigidity as a molded product, and its size and strength change are extremely small even when water is absorbed into its pores. Moreover, the durability of hydrophilicity was also excellent.

In order to fully demonstrate its performance as a hydrophilic open porous element that is effectively used in humidifiers, humidifiers, dew condensation preventers, humidity controllers, heat converters, etc., the tensile strength of the porous body must be 39k according to JIS 7113 test method
g/am” or more, JIS K ?20 as bending elastic modulus
2 x 103 kg/cm" or more according to the test method of 3. Furthermore, as for hydrophilicity, when a water droplet of about 0.3 cc is dropped onto the surface of a porous material, the time required for the water droplet to be completely absorbed into the porous material is Within 30 seconds, thickness 2cm, medium 2cm, height 1
5cm + water absorption height after 3 minutes when the lower end 1c11 of the rectangular plate is immersed in water + 1 (see Figure 1, 1 is a porous body, 2 is water) is more than 2cm, and the durability is 60℃
After the rectangular plate is immersed in hot water for 48 hours, the retention rate of the physical properties is 60% or more, and the increase in water droplet absorption time is 200% or less.The retention rate of the absorption height H is 50% or more. The dimensional change over time must also be about 1% or less.

The hydrophilic open porous body of the present invention fully satisfies these requirements and is suitably used as elements of humidifiers, moisturizers, dew condensation preventers, humidity controllers, heat exchangers, and the like.

(Example) In order to further clarify the present invention, a detailed explanation will be given below using Examples.

Example 1 Density 0.960 melt index (8 STMD 1) obtained by suspension polymerization method using Zieglanatsuta catalyst
238: Conditions = load 2.16 kg temperature 190°C) is 0.
1g/10 minutes, JIS Z-8801 (7) Particle size distribution and average particle size (50% particle size) according to JIS K6069 are shown in Table 1-1, and the total weight of 90% % has a particle size of 200 μm or less, and the bulk density at the angle of repose is 36 @ and 0.42, respectively, and 100 parts by weight of 4-polyethylene polymer powder and 0.0 parts of silica (Milton A manufactured by Mizusawa Chemical Co., Ltd.).
1 part by weight, 0.05 part of sodium valmityl sulfonate, and parts of sorbitan monolaure +-o, io were dry mixed while heating to 85°C in a high-speed mixer (Henschel mixer manufactured by Mitsui Miike). The obtained powder mixture was cut into a length of 16
The mixture was filled into the space of an aluminum mold having a space of 31 cm wide and 21 cm thick while being vibrated with a vibrator. The mold was then heated in a heating furnace until the surface reached 155° C. in order to sinter and shape the mixture, and then taken out and cooled in air. When I took out the molded product, the length was 160 mm.
A porous body having communicating pores with a width of 20 fins and a thickness of 2 fins was obtained. The porosity was measured and found to be 4.3%.

The tensile strength and bending rigidity of this porous body are determined by JIS
Measured according to K7113 and JISK7203. Furthermore, when about 0.3 cc of water was dropped onto the surface of the porous body using a dropper, it was completely absorbed into the porous body in about 15 seconds. The water suction height H when immersed in water is approximately 5 (:11
Met.

The resulting porous body was then immersed in 21 containers containing warm water at 60° C. for 48 hours, drained and dried, and its physical properties and hydrophilicity were measured. The results are shown in Table 1-2. Table 1-2 also shows the physical properties and dimensional changes of porous bodies that have sufficiently absorbed water. (The dimensional change is shown as the dimensional change rate (%) in the longitudinal direction.) As will be seen, the porous material obtained in this example has excellent hydrophilicity, physical properties, and durability for use in various elements. It can be seen that the change in dimensions and physical properties upon water absorption is extremely small.

Comparative Example 1.2 Evaluation was carried out in the same manner as in Example except that polyethylene polymer powder having the average particle size and particle size distribution shown in Table 1-1 was used. The results are shown in Table 1-2.

Comparative Example 3 Evaluation was carried out in the same manner as in Example 1 except that polyethylene polymer powder having a melt index of 0.5 was used. The results are shown in Table 1-2.

Comparative Example 4 Instead of the polyethylene object of Example 1, ethylene polymer powder was pelletized using an extruder and then ground again by mechanical grinding at room temperature to obtain a powder having the particle size distribution and powder properties shown in Table 1-1. . Evaluation was carried out in the same manner as in Example 1 except that this was used in place of the polyethylene in Example 2. Table 1 shows the results.
-2.

Example 2. 3. 4 Porous bodies were obtained and evaluated in the same manner as in Example 1, except that the amount of silica was changed as shown in Table 2-1, and calcium carbonate was added or used in combination. The results are shown in Table 2-3.

Comparative Example 5 A porous body was obtained and evaluated in the same manner as in Example 2 except for Example 1 in which no inorganic filler was added. The results are shown in Table 2-3.

Comparative Example 6 A porous body was obtained and evaluated in the same manner as in Example 2 except that the amount of silica added in Example 1 was changed to 4 parts by weight. The results are shown in Table 2-3.

Example 5.6.7 A porous body was obtained and evaluated in the same manner as in Example 1 except that the amounts of sodium palmitylsulfonate and sorbitan monolaurate were changed as shown in Table 2-1. The results are shown in Table 2-
Shown in 3.

Examples 8, 9.10 Same procedure as in Example 1 except that sodium lauryl sulfonate was used as the sulfonic acid type anionic surfactant and sorbitan monostearate was used as the sorbitan fatty acid ester surfactant. A porous body was obtained and evaluated. The results are shown in Table 2-4.

Comparative example? , 8.9 Porous bodies were obtained and evaluated in the same manner as in Example 1, except that the amount of surfactant was changed as shown in Table 2-2.

The results are shown in Table 2-4.

Example 11 The same procedure as in Example 1 was carried out except that in Example 2, 0.1 part of dry-mixed land water was allowed to coexist and the temperature during mixing was 90°C. The results are shown in Table 2-4.

Example 12 The same procedure as in Example 1 was carried out except that the temperature during dry mixing in Example 2 was 30°C.

The results are shown in Table 2-4.

Examples 13.14, 15, 16.17 In Example 2, as the nonionic surfactant, polyoxyethylene sorbitan monolaurate, polyethylene sorbitate tetraoleate, polyethylene glycol monolaurate, polyglycerin monocutstearate, The same procedure as in Example 1 was carried out except that 0.3 parts by weight of Glyarin monoprelate was used. The results are shown in Table 2-5.
It was shown to.

Example 18 Example 1 except that instead of the polyethylene powder in Example 1, a polyethylene powder obtained by pelletizing polymer powder using an extruder and freezing and pulverizing it and having the powder properties shown in Table 1-1 was used. I did the same thing. The results are shown in Table 2-5.
To/show.

[Brief explanation of the drawing]

FIG. 1 shows one of the methods for testing the hydrophilicity of a porous material in the present invention. (2) is a porous material, and (2) is water. Patent applicant: Asahi Kasei Industries, Ltd. Figure 1

Claims (1)

[Claims] 1) (a) A polyethylene powder, which has a melt index of 0.3 g/10 minutes or less and an angle of repose of the powder of 27°.
~40°, the particle size distribution has an average particle size (50% particle size) of 20~
At 150μ, more than 90% by weight of the entire particle size is 200μ or less,
100 parts by weight of polyethylene powder (A) having a bulk density of 0.30 to 0.55 g/cc and (b) an inorganic filler (B)
) 0.05 to 2.0 parts by weight, (c) sulfonic acid type anionic surfactant (C) 0 to 3.0 parts by weight, and (d) polyoxyethylene sorbitan fatty acid ester,
Nonionic surfactant 1 selected from polyoxyethylene sorbitol fatty acid ester, polyoxyethylene fatty acid ester, polyglycerin fatty acid ester, glycerin fatty acid ester, and sorbitan fatty acid ester
Species or mixtures of two or more species (D) 0 to 3.0 parts by weight and 3.0 parts by weight ≧ (C) + (D) ≧ 0.05 parts by weight (A), (B), (C ) and (D) components are mixed and sintered, and the hydrophilic porous body has an average porosity of 30 to 55% by volume.